1. Field of the Invention
The present invention relates to a position checking method, and more particularly, to a position checking method in which the mounting positions of ink tanks are specified in a recording apparatus.
2. Description of the Related Art
According to recent demands to further improve image quality, not only four popular color inks (black, yellow, magenta, and cyan), but also a light magenta ink and a light cyan ink having low density have been used. Further, the use of so-called particular color inks, such as a red ink and a blue ink, has been proposed. When these inks are used, seven or eight ink tanks corresponding to the colors are individually mounted in an inkjet printer. In this case, a mechanism is necessary to prevent the ink tanks from being mounted at wrong positions. Japanese Patent Laid-Open No. 2001-253087 discloses that the engaged portions between a carriage and ink tanks have different shapes. This prevents the ink tanks from being mounted improperly.
In order to specify the mounting positions of the ink tanks, the engaged portions between the carriage and the ink tanks have different shapes, as described above. In this case, however, it is necessary to produce ink tanks that have different shapes corresponding to the colors and types of ink. This is disadvantageous in terms of production efficiency and cost.
As another method, it is conceivable to separately provide different circuit signal lines of circuits, which are formed by connecting electrical contacts of ink tanks and electrical contacts provided at the mounting positions of the ink tanks in a carriage of a main unit, corresponding to the mounting positions. For example, it is conceivable to respectively provide different signal lines corresponding to the mounting positions in order to read ink color information from the ink tanks, and to control lighting of LEDs. When the color information read from any of the ink tanks does not correspond to the mounting position, it is determined that the ink tank is mounted improperly.
However, when the signal lines are thus separately provided corresponding to the ink tanks or the mounting positions, the number of signal lines increases. In particular, there is a tendency to improve image quality by increasing the number of types of inks in recent inkjet printers, as described above. In these printers, particularly, the increase in the number of signal lines increases the cost. A so-called bus connection using a common signal line is effective in reducing the number of signal lines. However, it is apparent that the ink tank or the mounting position of the ink tank cannot be determined by simply using a common signal line like a bus connection.
Accordingly, a position checking method is conceivable in which lighting of LEDs at mounting positions of a plurality of ink tanks is controlled by a common signal line, and in which the mounting positions of the ink tanks can be determined. However, the amount of emitted light varies among the LEDs, and therefore, the amount of light received by a light receiver provided in the printer also varies. For this reason, it is sometimes difficult to check the presence or absence of emitted light with reference to a threshold value depending on the amount of received light, and to thereby check the positions of the ink tanks. Although this problem can be solved by reducing the variation in the amount of emitted light, the cost is increased, for example, because there is a need to screen LEDs. A method has been proposed in which LEDs of a plurality of ink tanks mounted in a carriage are sequentially caused to emit light at predetermined positions during movement of the carriage, and in which the light emission is detected at the predetermined positions. In this position checking method, even when the amount of emitted light markedly varies among the LEDs of the ink tanks, it can be checked whether the ink tanks are mounted at correct positions. This allows the mounting positions of the ink tanks to be specified without increasing the cost.
In recent consumer-oriented inkjet printers, there is a tendency to attach importance to size reduction in order to increase sales function. For this reason, it is sometimes impossible to place a light receiver of a printer at a position best suited to the specification of the mounting positions of ink tanks, and to move the carriage so that all the ink tanks are placed at optimal positions.